Objectives: The proposed research effort is primarily concerned with the long range goal of better understanding the role of glutathione in ocular tissues especially including the lens, cornea and ciliary body. The present proposal for a five year period will be restricted to studies of the lens only. It is proposed that the role of glutathione in the lens be examined in the following ways: 1. Determination of glutathione concentration and the enzyme activity levels of the glutathione metabolic pathway during the development course (and in one case, regression) of cataracts induced by specific cataractogenic agents. 2. To further purify the enzymes of glutathione metabolism, to study their molecular properties and the effect of various cataractogenic agents, drugs and natural products upon the activity of the isolated enzymes. 3. Determination of the location of these enzymes within the lens using histochemical and immunological techniques with a view towards correlating their physical location with their physiological function. 4. Using cultured rabbit lenses, the normal active transport of specific neutral amino acids and catabolism of glutathione will be studied simultaneously, as well as the effects on these processes of specific inhibitors of the glutathione metabolic pathway.